The field of the invention is thermoplastic compositions.
Numerous attempts have been made to make useful products from wastes, especially rubber, plastic and paraffin wastes, all of which tend to be extremely resistant to natural degradation. U.S. Pat. No. 4,795,603, for example, teaches combining crushed rubber and plastic wastes to form an ebony-like configuration which is reported to be lightweight, and to have good hardness, water and weather resistance. As another example, Hungarian application T55270 A teaches mixing plastic polyurethane waste with rubber and paraffin oil to produce an injection moldable substance. Neither of these reference, however, teach how to combine use a waste rubber, a waste plastic and a heavy paraffin, which may also be a waste product. This is significant because such waste products may pose significant environmental problems, and are generally more difficult to utilize in manufacturing than virgin materials.
Issued U.S. Pat. No. 5,114,648 (xe2x80x9cthe ""648 patentxe2x80x9d) patent, which is incorporated by reference herein in its entirely, does teach processes for producing thermoplastic resin products which combines both waste rubber and waste plastic, along with a heavy paraffin. In the processes of the ""648 patent, a heated heavy paraffin distillate is pre-heated to a viscosity of approximating 0.70 Centipoise and then spray coated onto an at least partially vulcanized rubber composition. The resulting mixture is then combined with a thermoplastic, and the resulting combination is further reduced (as by mastication), extruded, and then molded or otherwise formed into a final product. The ""648 patent further teaches that the process could include granulating the vulcanized rubber to a predetermined mesh size, pre-processing contaminant removal, and could advantageously employ various processing parameters including use of a solvent having a boiling point of about 500xc2x0 F.-1000xc2x0 F. and a vapor density of about 8.0-13.0 Lbs/Cu.ft., pre-heating the paraffin distillate to about 180xc2x0 F., heating the rubber/distillate composition to about 220xc2x0 F.-250xc2x0 F. for a period of about 3.0 minutes.
At the time of filing the application which issued into the ""648 patent, it was thought that the processes claimed in that patent required the recited limitations. Those limitations, however, may have unnecessarily limited the usefulness of the claimed processes. Thus, there is a need to improve upon the claimed processes by eliminating various recited limitations.
The present invention is directed towards products and processes in which a reduced rubber composition is combined with a heavy paraffin and a reduced thermoplastic, wherein one or both of the rubber and thermoplastic are derived at least partially from waste products, and the resulting rubber/paraffin/thermoplastic material is further reduced while at an elevated temperature. In preferred embodiments the rubber is pre-processed by reduction to mesh sizes of about 0.25 inch and 0.5 inch respectively, and the heavy paraffin is pre-processed by being fluidizing to have a viscosity of at most about 1.0 Centipoise. It is also contemplated that the rubber and paraffin can be advantageously combined with each other prior to inclusion of the thermoplastic, with the paraffin/rubber combination being heated to a temperature of about 220xc2x0 F. to about 250xc2x0 F. for about 3 minutes. It is still further contemplated that the combination of rubber, paraffin and thermoplastic can be heated to between about 360xc2x0 F. and about 500xc2x0 F.